Method of and apparatus for varying the length of sound records



Apnl 9, 1935. B. FREUND 1,996,958

METHOD OF AND APPARATUS FOR VARYING THE LENGTH OF SOUND RECORDS FiledJune 19, 1931 2 Sheets-Sheet 1 II f, uululln ||l|||||||| lm mm!nl'lllHlllilllllllllllllllmllmlllllllflllll lllllllllllllllllllllllll 9-I I l 1 3/ ,1 l I i-- April 9, 1935. 1,996,958

METHOD OF AND APPARATUS FOR VARYING THE LENGTH OF SOUND RECORDS B.FREUND Filed June 19, 1931 2 Sheets-Sheet 2 XSIO Ill

Patented Apr. 9 1935 UNITED STATES PATENT OFFICE Berthold Freund,Berlin-Schoneberg, Germany I Application June 19, 1931, Serial No.545,582 In Germany June26, 1930 14 Claims.

My invention relates to apparatus for reproducing sound records which isequipped with means for scanning the record, for moving a record pastthe scanning means, and for reproducing the scanned sound record.

It is an object of my invention to provide an apparatus in which thedifliculty resulting from the necessity of running the sound record atthe same low velocity as the picture record with which it is analyzed,is eliminated.

To thisend, in my novel apparatus I provide means for varying therelative velocity of the sound record and the scanning means.

A film sound reproducer for analyzing sound film records is old in whichmeans are provided for reproducing repeatedly from a short length of therecord for ascertaining its synchronism with a picture film. Obviously,it is desirable to run the picture film slowly so that the operator canstudy all its details. On the other hand, if the sound record is run atthe same low velocity its pitch will be influenced so that,for-instance, a womans voice sounds like a mansin the reproduction, orthe pitch may even become so low as to render speech or songunintelligible or inaudible. All this is due to the fact that the pitchof the sound record reproduction is. determined by the velocity of thesound record.

According to my invention, the interdependence of the velocity of thesound record and the pitch of its reproduction is eliminated and thepitch of the reproduction isexclusively determined not by the velocityof the sound record but by its relative velocity, i. e., its velocityrelated to the velocity of the scanning means.

Any suitable means, such as a change-speed gear or the like, may beprovided for varying the relative velocity, and by such means the soundrecord is scanned in what will be referred to as sections for the sakeof convenience, the sections overlapping each other or being disposed atvarious relative distances.

It is understood that the sound record is not subdivided into sections,but that the expression sections relates only to the areas of the soundrecord which are subjected to scanning at a given time. The sections orareas are so very small and, even if at a distance from each other, areso near to each other that many of them are always in the range of thesame sound and so the reproduction does not become jerky orunintelligible. In fact, the portions or sections which are scannedcorrespond only to the individual sounds of the record, or even tofractions of such sounds.

By these means, the duration of every individual sound, or fraction of asound, in the record is protracted while, on the other hand, the pitchof the sounds is not altered even if the record moves quite slowly.

While the object in the old apparatus is to locate a. given portion ofthe film for scrutiny by repeated reproduction or scanning, and atreduced speed if desired, the object of my invention is to scan a filmat any desired speed which may belower or higher than its normal speed,but without varying the pitch of the sounds. Conversely, I may also movea film through my apparatus at normal speed and raise or lower the pitchof the sounds.

In my apparatus the low speed does not involve unintelligible speech.The sounds are only pro tracted but their pitch remains unaltered.

\ An absolutely satisfactory reproduction with my apparatus is notrequired for the purpose of synchronization and can only be obtained ifthe sound record curve is substantially uniform, that is, without veryprominent peaks. Peaks are present in the sound record curves ofpractically all words but it has been found that such normal. peaks arenot detrimental to the reproduction and that only the prominent peaksmay cause an imperfection in the reproduction which resemblesstammering, while the reproduction of music is not subject to suchimperfections at all. Prominent peaks correspond to the ejaculatedconsonants, such as b, p, d, t, g, k, etc. These consonants deterioratethe reproduction to some extent, but the major part of the human speechcorresponds to a record of substantially uniform jcurve. Such a curvecorresponds not only to the vocals a, e, i, o and u, but also to thesounding consonants, such as ,f, h, l, m, n, etc., and the correspondingrecord curves can be lengthened and shortened in the reproduction'asdesired, exactly as they can be protracted in the pronunciation, withoutaltering their pitch to such an extent that the pronunciation becomesunintelligible. Vocals and consonants represented by a substantiallyuniform record curve behave exactly like musical sounds if reproduced bymy apparatus. Only the prominent peaks corresponding to the aforesaidejaculated consonants, but not the normal peaks disturb the uniformityof the curve and are so short and irregular that the reproductionbecomes unnatural upon protraction. As mentioned, however, suchconsonants are in the minority and the other consonants and vocals arenot influenced. In the reproduction at reduced speed in my apparatus,the ejaculated consonants make the impression of the speech of a personwho pronounces defectively the said consonants. It follows that theintelligibility of the sound record is not by any means sacrificed inorder to maintain the pitch constant but that, on the contrary, thereproduction of a sound record, which by the manner in which it isscanned is chopped into the aforesaid spaced-apart or overlappingportions, is quite intelligible, apart from the slight imperfectionsreferred to at the reproduction of ejaculated consonants. In particular,the reproduction of a record with spaced-apart portions or sections isnot jerky as the sections are scanned so as to eliminate the spacesbetween-them. The length of the scanned portions of the record isreduced by this mode of scanning and the pitch is lowered for constantduration of the reproduction. The scanning is never interrupted. In ascanning apparatus as will be described below, a rotary disk with slotstherein is moved past an opening in a screen, and the relative distanceof the slots is equal to width of the opening in the screen so that whenone of the slots has moved past the area of the opening, the next slotenters the area. Nor is the reproduction of a record whose portions orsections overlap subject to confusion, because two or more portions ofthe record never are scanned at the same time but the individualportions or sections are scanned in succession and repeatedly. If thesections overlap instead of being spaced apart, the scanning operationextends over a longer distance for the same duration of reproduction sothat the pitch becomes higher. The difference consequently is that, forspacedapart sections, the length over which the scanning operationextends is shortened so that the relative scanning velocity is low, theduration of the reproduction being invariable, and the pitch is alsolow. Conversely, for overlapping sections the said length is increased,resulting in higher relative scanning velocity and higher pitch. But,for the reason stated, and on account of the smallness of the sections,confusion and interference is impossible with overlapping sections.

In the accompanying drawings, apparatus embodying my invention isillustrated more or less diagrammatically by way of example.

In the drawings,

Fig. 1 illustrates an apparatus having a fixed screen with a rectangularopening, and a rotary screen with slots,

Figs. 2, 3 and 4 are diagrams illustrating various operations of theapparatus,

Figs. 5, 6 and 7 show various screens for the apparatus in Fig. 1,

Fig. 8 shows an analyzing apparatus for sound records,

Fig. 9 shows a recording apparatus,

Fig. 10 shows an apparatus-for making shortened or lengthened recordsfrom normal records,

Fig. 11 is a diagram showing a picture and a sound record for asuperspeed camera,

Fig. 12 is a diagram showing a picture record and a sound record whichis to be shortened, and

Fig. 13 shows a combined superspeed sound and picture record.

Referring to Fig. 1, I is a record hearing medium, such as a film whoserecord is indicated by the shaded area, 20 is a rotary, and 22 is afixed screen. The rotary screen 20 has radial slots 2| and the fixedscreen 22 has a single rectangular opening 23. The width of the opening23 is exactly equal to the pitch of two radial slots 2|, as shown forthe slots 2I" and 2|. By suitably varying the ratio of the speed atwhich the film moves, to the constant speed at which the slots 2 I moveas the screen 20 rotates, i. e., the aforesaid relative velocity, and/orthe direction in which the film moves, with respect to the opening inthe fixed screen 22, various effects may be obtained, as will now bedescribed. If the record bearing film I is arrested while the screenrotates the section of the record which appears in the opening 23 isscanned repeatedly, and, if the section is small enough, the sound willbe continuous and uniform.

The sections which have been shown on the film I in several figures, forinstance in Fig. 2, are, it will be remembered, not real subdivisions ofthe record on the film, but their border lines are images indicating thedemarcation of areas subjected to the scanning operation at a giventime. The relative position of the sections, i. e., their spaced-apartor overlapping relation, is determined by the relative-velocity of thefilm I and the scanning means. In the example illustrated in Fig. 1, ithas been assumed that the disk 20 rotates at uniform velocity. Thevelocity at which the film moves is variable. Its velocity may be loweror higher than the velocity at which the slots 2| move past the opening23 in the screen 22. If it is higher, the sections on the film will bespaced apart, as shown in Fig. 3. If it is lower, the sections willoverlap, as shown in Fig. 4. A third possibility is that the velocitiesof the slots 2| and of the film are equal.

Nor isit necessary that the film should move in the same direction asthe slots, as will presently be assumed, for my invention also relatesto the relative direction of the scanning means and the film. Assume nowthat the film I moves from the left to the right as indicated by thearrow, and that the rotary apertured screen 20 rotates clockwise, asalso indicated by the arrow, the film I and the slots 2I' move past theopening 23 in the screen 22 in the same direction.

When the slotted disk 20 of Fig. 1 is stationary, and when the film bandI is advanced at the same time with the same speed as it was advanced inthe course of recording the sound record, the tone pitch remains thesame for both renditions, that is, the pitch of the sound record at thereproduction thereof is the same as the pitch of the record atrecording. However, when the slotted screen 20 rotates in the course ofreproduction in the direction indicated by the arrow in Fig. 1, therelative velocity between the scanning slots 2I and the sound recordbearer is less than when the screen is stationary. This results in alower pitch in the course of the same duration of reproduction. On theother hand, when the slotted screen 20 rotates in a direction oppositeto that indicated by the arrow in Fig. 1, the relative velocity betweenthe scanning slots 2I and the record on the record bearer is increased,resulting in an increase in the pitch of reproduction in the case thatthe advancing velocity of the film is not varied.

In the event that the film is advanced in the direction noted by thearrow in Fig. l, at a speed which is slower than its rate of advance atrecording, while at the same time the slotted screen 20 is rotated inthe direction opposite to that indicated by the arrow at such a speedthat the relative velocity between the scanning slots and the soundrecord is the same as that for a normal film speed and a stationarycondition of disk 20, a normal pitch is obtained despite the fact thatthe duration of the reproduction is lengthened. When the record consistsof speech or song, the individual words are clearly intelligible,although the duration of the reproduction as well as the individualtones are extended. Conversely, a hastened but understandable speech canbe obtained when the film is advanced at a faster rate at reproductionthan at recording when the disk 20 is rotated in the direction indicatedbyv the arrow in Fig. 1, at such a speed that in this case as well, therelative velocity between the slots 21 and the sound record is the sameas that when the film is advanced at normal speed and the screen isstationary.

It will be understood that the pitch is exclusively determined by therelative scanning velocity. being high for high scanning velocity, andlow for low scanning velocity.

If the record moves from the right to the left.

against the arrow in Fig. 9, while the screen 20 rotates as before,their speeds add, and the pitch is raised. If the speed of the record isless than that of the screen the operation will correspond to that ofthe diagram Fig. 4. On a photographic. film which is exposed to thelight traversing the scanned film l, the sections will be arranged asshown in the diagrams Figs. 2, 3 and 4,

according to the speed ratio at which the scanning operation isperformed. It the speeds are equal the half of each preceding sectionwill be duplicated. On a photographic film which is exposed to the lighttraversing the scanned film I, the sections will be arranged as shown inthe diagrams 2, 3 and 4, according to the speed ratio at which thescanning operation is performed. If the speed of the record becomeshigher than that of the screen only a portion of the section is repeatedwhich is less than .5.

Referring to Fig. 5, the opening in the fixed screen 22 is rhombicinstead of square as in Fig. 1 which results in a more gradual beginningand ceasing of the scanning by the slots 2| and the portions at thebeginning and the end are partly screened so that constant intensity anduninterrupted sequence of the sections are obtained. The base line ofthe rhombic opening is equal to the pitch of two slots.

Fig. 6 shows two screens 22. The screen at the left has an opening 23'in the shape of a trapezoid, and the opening 28" in the screen 22 at theright is semicircular.

Referring to Fig. 7, the sides of the opening 23" are curved at Ill and4|, with the object of so determining the intensities that thedisturbances in the scanning operation are reduced to a minimum.

Referring to Fig. 8, 59 is a motor, 50 is a record-bearing medium whichis wound on two reels one of which is rotated by the motor through thebelts or chains indicated, and 60 is a set of pulleys or sprocketsintermediate the motor and the reels for reducing the rate at'which thereels are driven. 52 is an endless belt which corresponds to the screen22, Fig. l, and has slots 2|, 2|", etc., like the screen 22. The screenor belt 52 is mounted on two pulleys one of which is actuated by themotor 59, and is equipped with a fly wheel 58. 53is a fixed screenhaving an opening such as shown in Figs. 1, 5, 6 and '1.

510 is a source of light at the left of the medium 50, 5 is a refectorby which the light from the source 510 .is projected onto the medium, 5|is a lens projecting a magnified image of the record on the medium 50 onthe belt 52 through the opening in the screen 53, 54' is a lens betweenthe two reaches of the belt 52, 55 is a photoelectric cell on which theimages from the sound are indicated by the reproducer 51.

If desired the belt 52 and the film 50 may be moved at two distinctspeeds and in the same or in opposite directions, as and for the purposedescribed with reference to Fig. 1.

Fig. 9 shows an apparatus for making sound records with an intermediaterecord bearing medium. 10 is a microphone, 1| is an amplifier, 13 is arecording magnet, and 12 is the intermediate record bearing medium. 14is a putting-out magnet. 15 is an endless chain which moves in parallelwith the medium 12, 16', 16", 16", etc., are scanning magnets onthechain, 11 is an amplifier under the control of the magnets, and 18 is asound reproducer connected to the amplifier. The chain 15 with themagnets 16' etc. is moved in the direction of the arrow, like the belt52, Fig. 8, and the record on the medium 12 is scanned.

Referring to Fig. 10, the apparatus illustrated in Fig. 8 is duplicatedhere as far as the photoelectric cell 55. 50 is a normal or originalrecord, 81 is the record to be obtained therefrom at a given rate whichis determined by the ratio at which the reels for the normal record 50and the record 81 are driven by a belt, chain or pulley 88, which ratiois controlled by the set of pulleys 60. v85 is an amplifier connected tothe cell 55, and 85 is a recorder. The record 81 is moved at a speedwhich is higher or lower than that of the normal record 50, and may movein the same direction as the record 50, or in opposite direction. Thesound may be recorded on 81 by any suitable means, such as photographic,mechanical, magnetic means, etc.

Referring now to Fig. 11, is a picture film from a super speed camera,with a considerably increased number of pictures. 96 is a sound recordor original which may have been made at normal speed and on a separatemedium. In order to obtain from these two films of different lengths asound and picture record, it is necessaryto increase the length of thefilm 96 until it is equal to that of the picture film 95. This-iseffected in the apparatus Fig. 10 by so determining the ratio of therecords 50 and 81 that the medium 81 moves faster than the medium 50while the slotted belt or screen 52 provides for the frequency whichcorresponds to the pitch of the sound. The two records, being of equallength, may now be combined on a single medium.

Conversely the sound record is shortened if the number of pictures inthe picture record is reduced, as shown in Fig. 12 where I01 is the longsound record, and 100 is the short picture record. Here the medium 81must move more slowly than the medium 50 whereupon the two records maybe combined on the same medium.

Fig. 13 shows the two records H0 and H l combined on a singlemedium.

In making superspeed records the sound record may be made directly onthe picture film or ona second medium moving at higher speed, asdescribed. However, as in this case the speed at which the sound recordis reproduced, is small, the pitch of the sound would become too low.This difilculty is overcome by the apparatus Fig. 10 by properlydetermining the speed of the slotted belt or screen 52. The normal pitchis reestablished in this manner and the records 50 and 81 move at thesame speed.

Suitable change-speed gears may be provided in the apparatus Figs. 8 and10 like the set of pulleys or sprockets 60 in Fig. 8.

I claim:

1. In an apparatus for reproducing sound rec-- ords, scanning means,means for moving said scanning means while reproducing the sound record,means for moving the record past said scanning means, and means forvarying the relation of the velocity of said record to the velocity ofsaid moving scanning means.

2. In an apparatus for reproducing sound records, scanning means, meansfor moving said scanning means while reproducing the sound record, meansfor moving the record past said scanning means, and means for varyingthe relative direction and the relation of the velocity of said recordto the velocity of said moving scanning means.

3. In an apparatus for reproducing sound records, scanning meansincluding a fixed screen with an opening therein and a slotted rotaryscreen adapted to cooperate with said fixed screen, means for rotatingthe slotted screen, means for moving the record past said scanningmeans, and means for varying the relation of the velocity of said recordto the velocity of said rotating screen.

4. In an apparatus for reproducing sound records, scanning means, meansfor moving said scanning means while reproducing the record, means formoving the record past said scanning means, means for magnifying saidrecord, and means for varying the relation of the velocity of saidrecord to the velocity of said moving scanning means.

5. In an apparatus for reproducing sound rec- 'ozds, scanning means,means for moving said scanning means while reproducing said record,means for moving a record past said scanning 'means, means for varyingthe relation of the velocity of said record to the velocity of saidmoving scanning means, and means for recording the sounds reproducedfrom said record.

6. The method of controlling the pitch of a sound record at reproductionwhich comprises advancing the sound record, scanning the sound recordwith movable scanning means, and adjusting the relation of the velocityof the sound record to the veloc ty of the movable scanning means.

7. The method of controlling the pitch of a sound record at thereproduction thereof when the sound record travels at a rate which isdifferentfrom that at the recording thereof which.

comprises scanning the sound record with a movable scanning means andadjusting at least the speed of the scanning means to render therelation of the velocity of the scanning means to the velocity of thesound. record thesame as that between the scanning means and the soundrecord at the recording thereof.

8. The method of controlling the pitch of a sound record at thereproduction thereof when the-sound record travelsat a rate which isdifferent from that at the recording thereof which comprises scanningthe sound record with a movable scanning means and adjusting the speedand the direction of movement of the scanning means to render therelation of the velocity of the scanning means to the velocity of thesound record the same as that between the scanning means and the soundrecord at the recording thereof.

9. The method of reproducing a sound record which comprises advancingthe. sound record, scanning the sound record with movable scanningmeans, and varying the ratio of the pitch of the sound record and therate of travel thereof by adjusting the direction and speed of movementof the scanning means relative to the speed of the sound record toobtain scanning sections of definite relative position.

10. The method of reproducing sound records which comprises varying theratio of pitch and running velocity of the sound records by scanningsaid records with movable scanning means and adjusting the speed of thescanning means relative to the speed of the sound record to obtainscanning sections of definite relative position.

11. The method of reproducing sound records which comprises varying theratio of pitch and running velocity of the sound records by scanningsaid records with movable scanning means and adjusting the speed anddirection of the movement of the scanning means relative to the speed ofthe sound record to obtain scanning sections of definite relativeposition.

12. The method of varying the ratio of pitch and running velocity ofsound records comprising scanning said records by varying the velocityof moved scanning means so as to obtain scanning sections of definiterelative position.

13. The method of varying the ratio of pitch and running velocity ofsound records comprising scanning said records by varying the velocityof moved scanning means so as to obtain spacedapart scanning sections.

14. The method of varying the ratio of pitch and running velocity ofsound records comprising scanning said records by varying the velocityof moved scanning means so as to obtain overlapped scanning sections.

IBERTHOLD FREUND.

